第29章

类别:其他 作者:Charles Darwin字数:5790更新时间:18/12/21 17:23:57
DuringourdifferentpassagessouthofthePlata,Ioftentowedasternanetmadeofbunting,andthuscaughtmanycuriousanimals。OfCrustaceathereweremanystrangeandundescribedgenera。One,whichinsomerespectsisalliedtotheNotopods(orthosecrabswhichhavetheirposteriorlegsplacedalmostontheirbacks,forthepurposeofadheringtotheundersideofrocks),isveryremarkablefromthestructureofitshindpairoflegs。Thepenultimatejoint,insteadofterminatinginasimpleclaw,endsinthreebristle-likeappendagesofdissimilarlengths——thelongestequallingthatoftheentireleg。Theseclawsareverythin,andareserratedwiththefinestteeth,directedbackwards:theircurvedextremitiesareflattened,andonthispartfivemostminutecupsareplacedwhichseemtoactinthesamemannerasthesuckersonthearmsofthecuttle-fish。 Astheanimallivesintheopensea,andprobablywantsaplaceofrest,Isupposethisbeautifulandmostanomalousstructureisadaptedtotakeholdoffloatingmarineanimals。 Indeepwater,farfromtheland,thenumberoflivingcreaturesisextremelysmall:southofthelatitude35degs。,Ineversucceededincatchinganythingbesidessomeberoe,andafewspeciesofminuteentomostracouscrustacea。Inshoalerwater,atthedistanceofafewmilesfromthecoast,verymanykindsofcrustaceaandsomeotheranimalsarenumerous,butonlyduringthenight。Betweenlatitudes56and57degs。southofCapeHorn,thenetwasputasternseveraltimes;itnever,however,broughtupanythingbesidesafewoftwoextremelyminutespeciesofEntomostraca。Yetwhalesandseals,petrelsandalbatross,areexceedinglyabundantthroughoutthispartoftheocean。Ithasalwaysbeenamysterytomeonwhatthealbatross,whichlivesfarfromtheshore,cansubsist;Ipresumethat,likethecondor,itisabletofastlong;andthatonegoodfeastonthecarcassofaputridwhalelastsforalongtime。ThecentralandintertropicalpartsoftheAtlanticswarmwithPteropoda,Crustacea,andRadiata,andwiththeirdevourerstheflying-fish,andagainwiththeirdevourersthebonitosandalbicores; IpresumethatthenumerouslowerpelagicanimalsfeedontheInfusoria,whicharenowknown,fromtheresearchesofEhrenberg,toaboundintheopenocean:butonwhat,intheclearbluewater,dotheseInfusoriasubsist? WhilesailingalittlesouthofthePlataononeverydarknight,theseapresentedawonderfulandmostbeautifulspectacle。Therewasafreshbreeze,andeverypartofthesurface,whichduringthedayisseenasfoam,nowglowedwithapalelight。Thevesseldrovebeforeherbowstwobillowsofliquidphosphorus,andinherwakeshewasfollowedbyamilkytrain。Asfarastheeyereached,thecrestofeverywavewasbright,andtheskyabovethehorizon,fromthereflectedglareoftheselividflames,wasnotsoutterlyobscureasoverthevaultoftheheavens。 Asweproceedfurthersouthwardtheseaisseldomphosphorescent;andoffCapeHornIdonotrecollectmorethanoncehavingseenitso,andthenitwasfarfrombeingbrilliant。Thiscircumstanceprobablyhasacloseconnectionwiththescarcityoforganicbeingsinthatpartoftheocean。Aftertheelaboratepaper,[8]byEhrenberg,onthephosphorescenceofthesea,itisalmostsuperfluousonmyparttomakeanyobservationsonthesubject。Imayhoweveradd,thatthesametornandirregularparticlesofgelatinousmatter,describedbyEhrenberg,seeminthesouthernaswellasinthenorthernhemisphere,tobethecommoncauseofthisphenomenon。Theparticlesweresominuteaseasilytopassthroughfinegauze;yetmanyweredistinctlyvisiblebythenakedeye。 Thewaterwhenplacedinatumblerandagitated,gaveoutsparks,butasmallportioninawatch-glassscarcelyeverwasluminous。Ehrenbergstatesthattheseparticlesallretainacertaindegreeofirritability。Myobservations,someofwhichweremadedirectlyaftertakingupthewater,gaveadifferentresult。Imayalsomention,thathavingusedthenetduringonenight,Iallowedittobecomepartiallydry,andhavingoccasiontwelvehoursafterwardstoemployitagain,Ifoundthewholesurfacesparkledasbrightlyaswhenfirsttakenoutofthewater。Itdoesnotappearprobableinthiscase,thattheparticlescouldhaveremainedsolongalive。Ononeoccasionhavingkeptajelly-fishofthegenusDianaeatillitwasdead,thewaterinwhichitwasplacedbecameluminous。Whenthewavesscintillatewithbrightgreensparks,Ibelieveitisgenerallyowingtominutecrustacea。 Buttherecanbenodoubtthatverymanyotherpelagicanimals,whenalive,arephosphorescent。 OntwooccasionsIhaveobservedthesealuminousatconsiderabledepthsbeneaththesurface。NearthemouthofthePlatasomecircularandovalpatches,fromtwotofouryardsindiameter,andwithdefinedoutlines,shonewithasteadybutpalelight;whilethesurroundingwateronlygaveoutafewsparks。Theappearanceresembledthereflectionofthemoon,orsomeluminousbody;fortheedgesweresinuousfromtheundulationsofthesurface。Theship,whichdrewthirteenfeetofwater,passedover,withoutdisturbingthesepatches。Thereforewemustsupposethatsomeanimalswerecongregatedtogetheratagreaterdepththanthebottomofthevessel。 NearFernandoNoronhatheseagaveoutlightinflashes。Theappearancewasverysimilartothatwhichmightbeexpectedfromalargefishmovingrapidlythroughaluminousfluid。Tothiscausethesailorsattributedit;atthetime,however,Ientertainedsomedoubts,onaccountofthefrequencyandrapidityoftheflashes。Ihavealreadyremarkedthatthephenomenonisverymuchmorecommoninwarmthanincoldcountries;andIhavesometimesimaginedthatadisturbedelectricalconditionoftheatmospherewasmostfavourabletoitsproduction。CertainlyIthinktheseaismostluminousafterafewdaysofmorecalmweatherthanordinary,duringwhichtimeithasswarmedwithvariousanimals。Observingthatthewaterchargedwithgelatinousparticlesisinanimpurestate,andthattheluminousappearanceinallcommoncasesisproducedbytheagitationofthefluidincontactwiththeatmosphere,Iaminclinedtoconsiderthatthephosphorescenceistheresultofthedecompositionoftheorganicparticles,bywhichprocess(oneistemptedalmosttocallitakindofrespiration)theoceanbecomespurified。 December23rd——WearrivedatPortDesire,situatedinlat。47degs。,onthecoastofPatagonia。Thecreekrunsforabouttwentymilesinland,withanirregularwidth。TheBeagleanchoredafewmileswithintheentrance,infrontoftheruinsofanoldSpanishsettlement。 ThesameeveningIwentonshore。Thefirstlandinginanynewcountryisveryinteresting,andespeciallywhen,asinthiscase,thewholeaspectbearsthestampofamarkedandindividualcharacter。Attheheightofbetweentwoandthreehundredfeetabovesomemassesofporphyryawideplainextends,whichistrulycharacteristicofPatagonia。Thesurfaceisquitelevel,andiscomposedofwell-roundedshinglemixedwithawhitishearth。Hereandtherescatteredtuftsofbrownwirygrassaresupported,andstillmorerarely,somelowthornybushes。Theweatherisdryandpleasant,andthefineblueskyisbutseldomobscured。Whenstandinginthemiddleofoneofthesedesertplainsandlookingtowardstheinterior,theviewisgenerallyboundedbytheescarpmentofanotherplain,ratherhigher,butequallylevelanddesolate;andineveryotherdirectionthehorizonisindistinctfromthetremblingmiragewhichseemstorisefromtheheatedsurface。 InsuchacountrythefateoftheSpanishsettlementwassoondecided; thedrynessoftheclimateduringthegreaterpartoftheyear,andtheoccasionalhostileattacksofthewanderingIndians,compelledthecoloniststodeserttheirhalf-finishedbuildings。Thestyle,however,inwhichtheywerecommencedshowsthestrongandliberalhandofSpainintheoldtime。 TheresultofalltheattemptstocolonizethissideofAmericasouthof41degs。,hasbeenmiserable。PortFamineexpressesbyitsnamethelingeringandextremesufferingsofseveralhundredwretchedpeople,ofwhomonealonesurvivedtorelatetheirmisfortunes。AtSt。Joseph’sBay,onthecoastofPatagonia,asmallsettlementwasmade;butduringoneSundaytheIndiansmadeanattackandmassacredthewholeparty,exceptingtwomen,whoremainedcaptivesduringmanyyears。AttheRioNegroIconversedwithoneofthesemen,nowinextremeoldage。 ThezoologyofPatagoniaisaslimitedasitsflora。[9]Onthearidplainsafewblackbeetles(Heteromera)mightbeseenslowlycrawlingabout,andoccasionallyalizarddartedfromsidetoside。Ofbirdswehavethreecarrionhawksandinthevalleysafewfinchesandinsect-feeders。Anibis(Theristicusmelanops——aspeciessaidtobefoundincentralAfrica)isnotuncommononthemostdesertparts:intheirstomachsIfoundgrasshoppers,cicadae,smalllizards,andevenscorpions。[10]Atonetimeoftheyearthesebirdsgoinflocks,atanotherinpairs,theircryisveryloudandsingular,liketheneighingoftheguanaco。 Theguanaco,orwildllama,isthecharacteristicquadrupedoftheplainsofPatagonia;itistheSouthAmericanrepresentativeofthecameloftheEast。Itisanelegantanimalinastateofnature,withalongslenderneckandfinelegs。Itisverycommonoverthewholeofthetemperatepartsofthecontinent,asfarsouthastheislandsnearCapeHorn。Itgenerallylivesinsmallherdsoffromhalfadozentothirtyineach;butonthebanksoftheSt。Cruzwesawoneherdwhichmusthavecontainedatleastfivehundred。 Theyaregenerallywildandextremelywary。Mr。Stokestoldme,thatheonedaysawthroughaglassaherdoftheseanimalswhichevidentlyhadbeenfrightened,andwererunningawayatfullspeed,althoughtheirdistancewassogreatthathecouldnotdistinguishthemwithhisnakedeye。Thesportsmanfrequentlyreceivesthefirstnoticeoftheirpresence,byhearingfromalongdistancetheirpeculiarshrillneighingnoteofalarm。Ifhethenlooksattentively,hewillprobablyseetheherdstandinginalineonthesideofsomedistanthill。Onapproachingnearer,afewmoresquealsaregiven,andofftheysetatanapparentlyslow,butreallyquickcanter,alongsomenarrowbeatentracktoaneighbouringhill。If,however,bychanceheabruptlymeetsasingleanimal,orseveraltogether,theywillgenerallystandmotionlessandintentlygazeathim;thenperhapsmoveonafewyards,turnround,andlookagain。Whatisthecauseofthisdifferenceintheirshyness?Dotheymistakeamaninthedistancefortheirchiefenemythepuma?Ordoescuriosityovercometheirtimidity? Thattheyarecuriousiscertain;forifapersonliesontheground,andplaysstrangeantics,suchasthrowinguphisfeetintheair,theywillalmostalwaysapproachbydegreestoreconnoitrehim。Itwasanartificethatwasrepeatedlypractisedbyoursportsmenwithsuccess,andithadmoreovertheadvantageofallowingseveralshotstobefired,whichwerealltakenaspartsoftheperformance。OnthemountainsofTierradelFuego,Ihavemorethanonceseenaguanaco,onbeingapproached,notonlyneighandsqueal,butpranceandleapaboutinthemostridiculousmanner,apparentlyindefianceasachallenge。Theseanimalsareveryeasilydomesticated,andIhaveseensomethuskeptinnorthernPatagonianearahouse,thoughnotunderanyrestraint。Theyareinthisstateverybold,andreadilyattackamanbystrikinghimfrombehindwithbothknees。Itisassertedthatthemotivefortheseattacksisjealousyonaccountoftheirfemales。 Thewildguanacos,however,havenoideaofdefence;evenasingledogwillsecureoneoftheselargeanimals,tillthehuntsmancancomeup。 Inmanyoftheirhabitstheyarelikesheepinaflock。Thuswhentheyseemenapproachinginseveraldirectionsonhorseback,theysoonbecomebewildered,andknownotwhichwaytorun。ThisgreatlyfacilitatestheIndianmethodofhunting,fortheyarethuseasilydriventoacentralpoint,andareencompassed。 Theguanacosreadilytaketothewater:severaltimesatPortValdestheywereseenswimmingfromislandtoisland。Byron,inhisvoyagesayshesawthemdrinkingsaltwater。SomeofourofficerslikewisesawaherdapparentlydrinkingthebrinyfluidfromasalinanearCapeBlanco。Iimagineinseveralpartsofthecountry,iftheydonotdrinksaltwater,theydrinknoneatall。Inthemiddleofthedaytheyfrequentlyrollinthedust,insaucer-shapedhollows。Themalesfighttogether;twoonedaypassedquiteclosetome,squealingandtryingtobiteeachother;andseveralwereshotwiththeirhidesdeeplyscored。Herdssometimesappeartosetoutonexploringparties:atBahiaBlanca,where,withinthirtymilesofthecoast,theseanimalsareextremelyunfrequent,Ionedaysawthetracksofthirtyorforty,whichhadcomeinadirectlinetoamuddysalt-watercreek。Theythenmusthaveperceivedthattheywereapproachingthesea,fortheyhadwheeledwiththeregularityofcavalry,andhadreturnedbackinasstraightalineastheyhadadvanced。Theguanacoshaveonesingularhabit,whichistomequiteinexplicable;namely,thatonsuccessivedaystheydroptheirdunginthesamedefinedheap。Isawoneoftheseheapswhichwaseightfeetindiameter,andwascomposedofalargequantity。